Last updated
Last checked 2026-11-07. Estimated tax rules and penalty rates change — always confirm the current figures on the official pages linked below.
Even if your paycheck already has tax withheld, this can still be your problem — a side income, a bonus paid separately, or a raise part-way through the year can leave you short by the time you file.
Put your income and withholding into the calculator on this page to see whether the four payments cover what you will owe — the penalty is easier to avoid than to reverse.
Estimated tax is the method for paying tax on income that is not covered by withholding. A salary with a Form W-4 usually has tax taken out of every paycheck, so the tax is paid as the year runs. Income that arrives without withholding — contractor work, business profit, and other payments that do not come with a paycheck — has no such mechanism, so the taxpayer has to send the tax in directly.
The obligation is about the timing of payments, not the total. The same tax is owed either way. What changes is whether it arrives in four installments during the year or in one lump with the return, and the penalty exists to make the timing matter.
If you have both a paycheck and untaxed income on the side, withholding may cover part of the bill, but the test is whether enough was paid in total and by when.
Each installment covers a period of the year, and the due date follows the end of that period (IRS):
| Period covered | Payment due |
|---|---|
| January 1 to March 31 | April 15 |
| April 1 to May 31 | June 15 |
| June 1 to August 31 | September 15 |
| September 1 to December 31 | January 15 of the following year |
The periods are not equal in length. The second covers two months and the third covers three, which is why the gaps between the dates are uneven. The schedule is set by rule, not by the calendar's convenience.
If a due date falls on a Saturday, Sunday, or legal holiday, the payment is on time if it is made the next business day (IRS). A payment that is a day late for another reason is late, and that period's calculation will show it.
The penalty is not automatic for everyone who pays estimated tax late. There are two ways to stay clear of it, and either one is enough (IRS Topic 306):
1. Owe less than $1,000. If the tax left after subtracting withholding and refundable credits is under $1,000, the underpayment penalty does not apply.
2. Pay enough in advance. Pay at least 90% of the tax for the current year, or 100% of the tax shown on the prior year's return — whichever is smaller.
The second test is the one that makes planning possible: it lets a taxpayer who expects more income this year base the payments on last year's known figure and settle the difference at filing. Because the smaller of the two controls, meeting one is enough.
The IRS notes that special rules apply to taxpayers with income from farming or fishing, to certain household employers, and to certain higher-income taxpayers (IRS Topic 306). Those cases should be checked against the current instructions rather than assumed to follow the two tests above.
It is tempting to read a refund at filing as proof that the payments were fine. It is not.
The IRS states that you may be charged a penalty even if you are due a refund when you file your return (IRS Publication 505). The penalty is not about the final balance. It is about whether enough tax was paid by each due date during the year.
A taxpayer can overpay overall and still have underpaid in April. The refund arrives because the total was too high; the penalty arrives because the timing was too late. Both can be true on the same return.
The underpayment penalty is calculated separately for each payment period (IRS Publication 505). A large payment in January does not retroactively fix a shortfall in April. Each period is tested on its own, and the penalty for that period is computed on the amount that should have been paid by that date.
The calculation is done on Form 2210, Underpayment of Estimated Tax by Individuals, Estates, and Trusts, which is also the form used to determine whether a penalty is owed (IRS Topic 306).
The form applies an annual rate to the underpayment for the relevant rate periods. In the Form 2210 worksheet, the rate for the rate periods from April 16, 2025 through April 15, 2026 is 7% (IRS instructions for Form 2210). The rate is set for defined periods, so a return that spans more than one period can use more than one rate.
Two practical consequences follow. First, the earlier a shortfall happens, the longer it runs and the more it costs. Second, paying extra late in the year is better than not paying, but it does not erase the earlier periods.
For an employee, the most direct fix is to give the employer a new Form W-4 to change withholding (IRS Publication 505). This can be done mid-year; there is no need to wait for the next tax season.
Changing withholding is often simpler than making a separate estimated payment, because the extra tax comes out of each paycheck automatically. The IRS publishes a withholding estimator that produces the Form W-4 to hand in (IRS).
For income that has no withholding at all, the equivalent step is to raise the remaining estimated payments so that the year's total reaches one of the safe-harbor amounts. Our suggestion is to check the year-to-date total after each due date rather than at filing time: by December the remaining periods are too few to absorb a large gap.
The penalty is determined on the return, so the first step is to complete Form 2210 and see what the calculation actually produces (IRS Topic 306). The form identifies which periods were short and by how much.
From there, the useful move is to bring the next payment up to the level the safe harbor requires, so the remaining periods do not add to the total. Waiting until the return is filed leaves every remaining period short as well.
This page describes federal estimated tax for individuals. State estimated tax, corporate estimated tax and the special rules listed above are separate questions with their own forms and dates.
Check the year-to-date position in the calculator on this page before the next due date, not after it.
Updated 2026-11-08 · Sources retrieved 2026-11-07
This is a general explanation of federal estimated tax for individuals, not tax advice. It does not cover state estimated tax, corporate estimated tax, or the special rules that apply to farmers, fishers, household employers and certain higher-income taxpayers. Your own result depends on your full return. For anything you will act on, check the IRS pages linked above or ask a tax professional.
We check every report against the official source and update the page. See how on our Corrections.